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Kathleen S. Wilson and Kevin S. Spink

Purpose: The use of self-efficacy to predict physical activity has a long history. However, this relationship is complex, as self-efficacy is thought to influence and be influenced by physical activity. The directionality of the self-regulatory efficacy (SRE) and physical activity relationship was examined using a cross-lagged design. A secondary purpose was to examine these relationships across differing weather conditions. Methods: Canadian adolescents (N = 337; aged between 13 and 18 years) completed the physical activity and SRE measures 4 times during a school year. Structural equation modeling was used to perform a cross-lag analysis. Results: The relationships between physical activity and SRE appeared to be weather dependent. During a more challenging weather period (eg, cold weather), the relationship between physical activity and SRE was bidirectional. However, no relationship emerged when the 2 constructs were assessed during a more optimal weather period (eg, warm weather). Conclusions: Some support has been provided for the bidirectional nature of the relationship between physical activity and SRE. The relationship appeared to be qualified by climate considerations, suggesting that future research examine how weather may relate not just to physical activity but also to the correlates of physical activity.

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Benjamin J. Narang, Greg Atkinson, Javier T. Gonzalez and James A. Betts

The analysis of time series data is common in nutrition and metabolism research for quantifying the physiological responses to various stimuli. The reduction of many data from a time series into a summary statistic(s) can help quantify and communicate the overall response in a more straightforward way and in line with a specific hypothesis. Nevertheless, many summary statistics have been selected by various researchers, and some approaches are still complex. The time-intensive nature of such calculations can be a burden for especially large data sets and may, therefore, introduce computational errors, which are difficult to recognize and correct. In this short commentary, the authors introduce a newly developed tool that automates many of the processes commonly used by researchers for discrete time series analysis, with particular emphasis on how the tool may be implemented within nutrition and exercise science research.

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Blair Crewther, Christian Cook, John Fitzgerald, Michal Starczewski, Michal Gorski and Joanna Orysiak

Purpose: Reported associations between vitamin 25(OH)D and exercise performance are equivocal, perhaps due to complex interplay with cortisol and testosterone. In this study, the authors investigated serum 25(OH)D and cortisol as moderators of the testosterone relationship with exercise performance in adolescent male athletes. Methods: A total of 88 ice hockey players were assessed for serum 25(OH)D, cortisol, testosterone, body composition, and exercise performance, based on countermovement jump power and muscle torque. The authors tested independent relationships, before examining complex interactions via moderated regression analyses. Results: Most athletes (62.5%) exhibited a suboptimal (20–30 ng·mL−1) serum 25(OH)D concentration, whereas 9.1% of athletes were deficient (<20 ng·mL−1). Serum 25(OH)D was not related to performance when controlling for testing year, age, and fat mass. Further modeling revealed a significant hormonal interaction. Specifically, in low-25(OH)D subjects, testosterone predicted countermovement jump power at a high (β = 7.10, effect size = .43, P < .01), but not low (β = −3.32, effect size = −.20, P = .09), cortisol concentration. Conclusions: Serum 25(OH)D was a poor predictor of exercise performance, but it did moderate (with cortisol) the testosterone link to muscle power. Notably, this relationship emerged among individuals with a 25(OH)D concentration (∼22 ng·mL−1) approaching the deficiency cutoff. Viewing 25(OH)D as a moderating, rather than dose responsive, variable could help explain equivocal cross-sectional associations.

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Daniel H. Aslan, Joshua M. Collette and Justus D. Ortega

The decline of walking performance is a key determinant of morbidity among older adults. Healthy older adults have been shown to have a 15–20% lower walking economy compared with young adults. However, older adults who run for exercise have a higher walking economy compared with older adults who walk for exercise. Yet, it remains unclear if other aerobic exercises yield similar improvements on walking economy. The purpose of this study was to determine if regular bicycling exercise affects walking economy in older adults. We measured metabolic rate while 33 older adult “bicyclists” or “walkers” and 16 young adults walked on a level treadmill at four speeds between (0.75–1.75 m/s). Across the range of speeds, older bicyclists had a 9–17% greater walking economy compared with older walkers (p = .009). In conclusion, bicycling exercise mitigates the age-related deterioration of walking economy, whereas walking for exercise has a minimal effect on improving walking economy.

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Brian Catania, Travis Ross, Bradley Sandella, Bradley Bley and Andrea DiTrani Lobacz

Context: Training and assessment of the abdominal and trunk muscles are widely used in the clinical setting. However, it is unknown what types of exercises are most effective in activation of both the global and local stabilizers in these regions. Objective: The purpose of this study was to establish the reliability of a novel clinical screening tool (sling screen) to assess the muscles of the abdomen and trunk. The second aim was to use the clinical screening tool and musculoskeletal ultrasound to compare the effects of a rotary-based exercise program that targets both the global and local muscles to the effects of a traditional exercise program on the activation of the abdominal and trunk muscles. Design: Double-blind, randomized controlled trial. Setting: Sports medicine facility. Participants and Interventions: Thirty-one healthy participants were randomly allocated to receive a single-session rotary-based or traditional “core” exercise program. Main Outcome Measures: The participants were assessed at the baseline and immediately postintervention. The primary outcome measures were muscle thickness examined by musculoskeletal ultrasound and clinical examination of muscle activation using a screening tool. The data were collected by blind assessors. Reliability and validity of a clinical screening tool (sling screen) were also assessed. Results: The analysis of the covariance tests showed a significant increase in oblique thickness for the rotary exercise group. All participants displayed a significant increase in multifidus thickness. The Wilcoxon signed-rank tests revealed a significant increase in clinical assessment scores in the rotary exercise group but not the traditional exercise group. Reliability of the sling screen ranged from moderate to good. Conclusion: This clinical trial provides evidence that a rotary-based exercise program may be more effective in producing increases in oblique muscle thickness than traditional “core” exercises in young, healthy adults. The sling screen tool was able to identify these muscle thickness changes. Future studies should investigate how these results correlate to injury risk, other populations, and also how to implement the sling screen into clinical practice.

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Shuge Zhang, Ross Roberts, Tim Woodman and Andrew Cooke

Narcissism–performance research has focused on grandiose narcissism but has not examined the interaction between its so-called adaptive (reflecting overconfidence) and maladaptive (reflecting a domineering orientation) components. In this research, the authors tested interactions between adaptive and maladaptive narcissism using two motor tasks (basketball and golf in Experiments 1 and 2, respectively) and a cognitive task (letter transformation in Experiment 3). Across all experiments, adaptive narcissism predicted performance under pressure only when maladaptive narcissism was high. In the presence of maladaptive narcissism, adaptive narcissism also predicted decreased pre-putt time in Experiment 2 and an adaptive psychophysiological response in Experiment 3, reflecting better processing efficiency. Findings suggest that individuals high in both aspects of narcissism perform better under pressure thanks to superior task processing. In performance contexts, the terms “adaptive” and “maladaptive”—adopted from social psychology—are oversimplistic and inaccurate. The authors believe that “self-inflated narcissism” and “dominant narcissism” are better monikers for these constructs.

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Hayley M. Ericksen and Rachele E. Vogelpohl

Anterior cruciate ligament (ACL) injury in female athletes is common. Team sport athletes experience more ACL injuries than ballet and modern dancers. Examining biomechanical differences between these two groups may help to explain the discrepancy in ACL injury rates. The purpose of this study was to examine lower extremity kinematic differences between collegiate dancers and National Collegiate Athletic Association Division I soccer athletes during a rebound jump-landing task. Peak hip, knee, and ankle kinematics were collected during a jump-landing task. Results showed more knee flexion and less ankle eversion in the dancers compared to the soccer athletes. Differences in training and strategies used during landing may explain the kinematic differences between groups.

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David Eitle, Steven Swinford and Abagail Klonsinski

Using data from the Add Health, the authors consider whether male high school sport participation had an association with intimate partner violence perpetration into adulthood, controlling for other known predictors. Results show that sport participation is associated with a reduced risk of perpetrating intimate partner violence in adulthood, which the authors interpret as generally supportive of the deterrence hypothesis, the notion that playing sport promotes prosocial values, increases supervision, and increases bonding to conventional institutions that lower the risk of engaging in violent behavior against women. However, the inclusion of measures representing this hypothesis failed to attenuate the sport participation–intimate partner violence association, raising questions about whether the deterrence hypothesis is the appropriate explanation.

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Madison Ardizzi, Brian Wilson, Lyndsay Hayhurst and Janet Otte

Bicycles have been hailed by the United Nations and nongovernmental organizations for use in social and economic development. However, there is a lacuna of research exploring the value of bicycles for development (BFD) outside of Europe and America. Specifically, there is a lack of research on the structure and perspectives of BFD organizations. This study draws on 19 semistructured interviews with BFD organizations in various regions of Uganda. We found that (a) BFD organizations exist along a spectrum from community-based to international, (b) the meanings ascribed to the bicycle are unstable and context dependent, and (c) that there were a range of ways that bicycles were seen to lead to positive outcomes—although barriers to attaining these outcomes were identified too. The authors conclude by suggesting that while bicycles are considered useful for a range of development purposes, perspectives on their usefulness vary—as inequalities commonly associated with sport for development are evident in the BFD movement too.